The present invention relates to a power saving controller designed to be added to any HID fixture with an absolute minimum of wiring. In particular, it eliminates a separate supply to power the control circuits by extracting current from the lamp being controlled.
All prior art incorporated means for reducing the applied voltage or limiting the current through a xe2x80x9closslessxe2x80x9d mechanism. The difference in this case is how the lossless device is incorporated and how it is powered and controlled.
Assuming a HID lamp there are two general categories of such dimmers. They are: (1) Reduce the applied primary input power by: (a) Step down transformer (conventional or autotransformer), (b) Insert a lossless reactance to drop the voltage without attendant dissipation, (c) Limit the applied energy by a solid state switch, which does not continuously conduct. (Switching power supply).
Secondly, many inventors and manufacturers have concentrated on making or modifying a fixture, which has dimmable capabilities. These have followed similar approaches: (a) Step down transformer, (b) Adding a xe2x80x9closslessxe2x80x9d reactance, (c) Duty cycle switching.
Since each of these features have some intelligence, they require a power supply for the control logic. These power supplies are usually connected to the primary supply with its attendant problems. Powering from a variety of sources increases manufacturing and installation costs because of the wide variety of commercial power supply voltages.
Any modifications or connection to the primary supply is quite complicated because of the wide variety of voltages available. Moving the control power supply physically inside the ballast doesn""t eliminate the complexities associated with such a variety of supply voltages.
Power reduction in HID lamps is currently achieved by reducing the lamp current by reducing the capacitance of the series capacitor. In the majority of installations this is achieved by employing two capacitors whose sum is equal to the value required for maximum brightness. Dimming is achieved by switching out one these capacitors leaving only the desired low value.
The object of this invention is to absolutely minimize the installation labor and costs so that the modification investment may be recovered as quickly as possible. Toward this end the installed ballast is left intact and the lamp series capacitor value is reduced by adding another capacitor externally. The internal capacitor is left unchanged. To return to full brightness the external capacitor is shorted.
Dimming the lamp is only one aspect of the changes required. To be effective the dimming must be intelligent and provide normal light levels when required. It must also be intelligent enough to dim the lights when the area is unoccupied. Control implies electronics, which in turn implies power for operation. Inside the ballast enclosure mains power is available but this comes in a wide range of voltages, 120 to 408VAC, which complicates their use in a modification kit. None of these are available at the lamp. The voltage across the lamp, and the current through it varies widely during warm-up and run.
The invention describes a current transformer in series with the lamp, which is able to derive power for the control electronics during the entire lamp operational cycle. Timing is provided from lamp turn-on To insure that the lamp reaches a stable operating temperature before dimming is enabled.
Sufficient power is obtained from the series transformer to also power the associated sensors mounted externally and the internal RF transmitter or receiver, mounted within the SPMK enclosure.
Sensors are relatively expensive, so it is advantageous to minimize the number required for a complete building modification. Toward this end the SPMK incorporates a coded RF transmitter to allow a single sensor to control the dimming of groups of lamps. This is accomplished through companion SPMK units equipped with RF receivers. Through the use of addressing and coding a single lamp may be controlled by more than one SPMK transmitters.
The receiver version of the SPMK allows the use of a variety of controlling sources in addition to the SPMK transmitter. Hand-held, wall-mounted sensors, vehicle-mounted, transmitters etc. all may be employed in any mixture.
All of this power saving capability is achieved by modifying only one of the two wires exiting the ballast to the HID lamp. Any lamp in the range of 175 to 1000 watts may be controlled. The SPMK electronics including a receiver or transmitter and antenna is mounted in the SPMK enclosure. The sensor is either mounted on the SPMK enclosure or on the luminaire itself.